GB2298417A - Safety keg and spear valve assembly - Google Patents

Abstract

A safety keg assembly comprises a keg including a keg neck, and a safety spear valve adapted to be sealed in the keg neck by sealing means and having a valve body, the outer wall of the valve body confronting the inner wall of the keg neck when the safety spear valve is in position, a key on one of the valve body or the keg neck, and a keyway for receiving the protrusion in the other of the valve body or keg neck, the keyway (4) comprising an opening (3) allowing the key to enter the keyway, a first recess (5) in the keyway axially spaced from the opening and into which the key may be positioned by circumferential and axial movement of the spear valve to allow the spear valve to be sealingly positioned in the keg neck, and a second recess (10) in the keyway axially aligned with the first recess (5) whereby, if pressurized gas is present within the keg when an attempt is made to release the spear valve, the key will move from the first recess to the second recess by means of the residual pressure preventing angular movement of the spear valve assembly and the seal between the spear valve and the keg neck will be broken, allowing simultaneous venting of the residual pressure. The keyway may be configured as a screw thread.

Description

SAFETY KEG ASSEMBLY This invention relates to a safety keg assembly including a keg and a safety spear valve and also to a safety spear valve therefor.

A beer keg is usually a substantially cylindrical drum having a mouth at one end which is closed by a spear valve assembly providing access to beer in the keg via a tapping head. The spear valve assembly usually comprises a beer valve located in the keg neck which includes a valve body and a valve housing, and a downtube connected to the valve body which extends into the keg. On site, a tapping head is connected to the spear valve providing pressure in the form of CO2, allowing the beer to be supplied under pressure to a dispensing tap at a bar.

It has been recognized that problems can occur when the spear valve is being removed from the keg if there is residual CO2 pressure within the keg. If the gas is not evacuated prior to an attempt to open the keg, it can result in the spear valve being blown out of the keg by the residual gas. This is, of course, very dangerous and likely to cause injury, particularly in the event of unauthorized or unskilled attempts at removal of the spear valve.

One arrangement for addressing this problem is disclosed in G.B. Patent No. 2062789B which discloses a protrusion on the spear valye assembly which co-operates with a first keyway, groove and a second keyway formed in the keg neck. When the spear valve assembly is in its proper position, the protrusion or key on the spear valve assembly is located in the second keyway. If removal of the spear valve assembly is attempted whilst there is a residual pressure in the keg, the pressure will force the valve assembly upwards, but the key or protrusion will simply engage the top of the groove rather than passing through the first keyway because this is circumferentially offset from the second keyway.

An alternative proposal addressing the same problem is disclosed in G.B. Patent No. 2158906B which is directed to a beer keg valve system including a co-operating protruding abutment on the keg neck and a female screw thread on the spear valve assembly. The co-operation between the two parts draws the valve assembly into the keg neck on rotation of the valve assembly with respect to the keg neck. The upper and lower ends of the screw thread are open to provide a venting path allowing venting of gas from the keg via the groove on commencement of release of the valve assembly from the keg neck.In addition, in the event that there is residual pressure within the keg, a safety recess is formed in the screw thread intermediate the ends so that the abutment is forced into the recess by the keg pressure, preventing further rotation of the spear valve assembly without actual movement of the spear valve assembly to release the protrusion from the safety recess.

In both these arrangements, it is possible to accidentally bypass the safety arrangements because it is still relatively easy to rotate the spear relative to the keg neck with the result that the spear valve assembly will be blown out of the keg neck under the force of the residual pressure in the keg.

An object of the present invention is to provide an improved assembly.

According to the present invention, a safety keg assembly comprises a keg including a keg neck, a safety spear valve adapted to be sealed in the keg neck by sealing means and having a valve body, the outer wall of the valve body confronting the inner wall of the keg neck when the safety spear valve is in position, a key on one of the valve body or the keg neck, and a keyway for receiving the protrusion in the other of the valve body or keg neck, the keyway comprising an opening allowing the key to enter the keyway, a first recess in the keyway axially spaced from the opening and into which the key may be positioned by circumferential and axial movement of the spear valve assembly to allow the spear valve to be sealingly positioned in the keg neck, and a second recess in the keyway axially aligned with the first recess whereby, if pressurized gas is present within the keg when an attempt is made to release the spear valve, the key will move from the first recess to the second recess by means of the residual pressure preventing angular movement of the spear valve assembly and the seal between the spear valve and the keg neck will be broken, allowing simultaneous venting of the residual pressure.

Preferably, the keyway is formed in the valve body of the spear valve assembly and the opening comprises a substantially vertical slot portion opening into a circumferential or arcuate slot portion, the first recess being a second vertically extending slot portion circumferentially and axially offset from the opening. Alternatively, the keyway may be a slot configured in the manner of a screw thread in order to draw the spear valve assembly into the keg neck as the key moves along the slot from the opening to its locking position in the first recess.

The invention also includes a spear valve assembly for a safety keg assembly as aforesaid.

The invention will now be described by way of example, with reference to the accompanying drawings in which: Figures 1A and 1B disclose a first existing safety arrangement; Figure 2 discloses a second existing arrangement similar to that disclosed in Patent No. 2158906B discussed above; Figures 3A and 3B show the arrangement of Figure 1A and Figure 1B modified in accordance with the invention; Figures 4A and 4B contrast the arrangement of the present invention with the standard profile of the prior art in more detail; Figure 5 shows the inter-engagement of the spear valve assembly of Figure 4A with a keg neck partly in section; Figure 6 shows an exploded view of the arrangement shown in Figure 5; Figure 7 shows a second embodiment of the invention; and, Figure 8 shows a third embodiment of the invent ion.

In the prior art arrangement of Figure 1A and Figure 1B, the valve body (1) of a spear valve assembly includes a keyway or slot (2) comprising a short vertical slot portion (3) open at its lower point, a continuous horizontal slot portion (4) and a second vertical slot portion (5) set at 1800 to the slot portion (2). On the inside wall of the keg neck, there is a key or protrusion (not shown) which co-operates with the slot (2) in the valve body. In order to insert the spear valve assembly into the keg neck, the protrusion enters the slot (2) through the vertical portion (3) and is then pushed down and rotated so that the protrusion passes along the slot portion (4) until the protrusion is aligned with the vertical slot portion (5). The rotation is carried out with downward loading applied against the spear valve assembly to allow the protrusion to enter the vertical slot portion (5) and then the spear valve assembly is locked into position by means of a retaining ring (not shown). Accordingly, in the assembled position, the protrusion is positioned in the vertical slot portion (5) and preferably a second protrusion is positioned in the vertical slot portion (3) thereby preventing the spear valve from angular movement.

In order to release the spear valve assembly from the keg neck, the retaining ring is disengaged by means of a special tool (not shown).

The spear valve assembly is then unlocked and may be raised to such a point that the first protrusion comes into contact with the lowermost face of the slot portion (4) aligned with the vertical slot portion (5) thereby preventing the spear valve assembly from being ejected if the keg is pressurized. However, we have found that, with the spear valve assembly in this partly raised position, although the gas at pressure within the keg should escape so making the keg safe, this does not always happen, possibly because an Oring used to seal between the keg neck and the spear valve assembly is still in contact with its respective sealing faces.

The prior art arrangement of Figure 2 is designed to alleviate this problem in that, on releasing the spear valve assembly, the protrusion moves from an open slot portion (6) to an open slot portion (7) via an elongate slot portion (8) and a small safety recess (9) is provided intermediate the extent of the slot so that, in the event of residual pressure remaining within the keg, the protrusion is forced into the safety recess (9) preventing further angular movement and therefore preventing the spear valve assembly from being ejected from the keg neck until the residual pressure has been released. However, we have found with this prior art arrangement that it is possible to rotate the spear valve body relative to the neck of a pressurized keg with such ease that the protrusion does not engage with the safety recess (9) despite the presence of residual pressure.

In accordance with the invention, the prior art arrangement of Figures 1A and 1B is modified as shown in Figures 3A and 3B by providing a safety slot portion (10) which is axially aligned with the vertical slot portion (5) into which the protrusion on the keg neck is positioned in the fully assembled condition of the keg assembly.

The arrangement of this invention has the following two advantages: (i) if pressurized gas is present within the keg and the retaining ring is released, the spear valve assembly will be raised by the residual pressure so that the protrusion on the keg neck immediately enters the safety slot portion (10) so locking the spear valve assembly and preventing any rotation and also possible ejection from the keg; (ii) when the protrusion is in the safety slot portion (10), this also allows the spear valve assembly to stand higher in the keg neck thereby ensuring that the O-ring used to seal between the keg neck and the spear valve assembly is clear of its sealing surface so making depressurization of the keg certain.

The arrangement of Figures 4A, 5 and 6 is a more detailed explanation of the invention shown diagrammatically in Figures 3A and 3B and the same parts have been accorded the same numbers.

Accordingly, one can see from comparison of Figures 4A and 4B that the safety recess (10) is aligned with the vertical slot portion (5) whereas in Figure 4B the lower surface of the slot portion (4) has a flat lateral face.

In Figures 5 and 6 the spear valve assembly (11) is shown in co-operation with the keg neck (12). In order to prevent the spear valve assembly (11) from being ejected accidentally from the keg neck (12), the protrusions (13) and (14) on the inside surface of the keg neck co-operate with the slot (2) in the valve body (1). Figures 5 and 6 show more detail of the spear valve assembly which comprises a depending downtube (15), a skirt (16) having openings (17) allowing the keg to be filled with beer through the openings through a flowpath normally closed by a valve (18) biassed into its closed position by spring (19). In its lowermost position, an Oring (20) on the spear valve assembly engages against the sealing surface on the inside of the keg neck which seals between the keg neck and the spear valve assembly.

Figure 7 shows an alternative arrangement where the slot portion (4) does not extend circumferentially around the valve body over the entire circumference of the valve body. In addition, the slot is open to the top at the vertical slot portion (5) as well as to the bottom at the slot portion (3). In this arrangement, the safety slot portion (10) can be seen axially aligned with the slot portion (5).

The arrangement of Figure 8 is similar to that of Figure 7 except that the vertical slot portion (5) is closed rather than open.

Although the details of the invention have been described with the slot formed in the valve body and the protrusions being on the inside of the keg neck, it will be appreciated that the slot could be formed in the keg neck and the protrusion being on the valve body.

Claims (4)

1. A safety keg assembly comprising a keg including a keg neck, a safety spear valve adapted to be sealed in the keg neck by sealing means and having a valve body, the outer wall of the valve body confronting the inner wall of the keg neck when the safety spear valve is in position, a keg on one of the valve body or the keg neck, and a keyway for receiving the protrusion in the other of the valve body or keg neck, the keyway comprising an opening allowing the key to enter the keyway, a first recess in the keyway axially spaced from the opening and into which the key may be positioned by circumferential and axial movement of the spear valve assembly to allow the spear valve to be sealingly positioned in the keg neck, and a second recess in the keyway axially aligned with the first recess whereby, if pressurized gas is present within the keg when an attempt is made to release the spear valve, the key will move from the first recess to the second recess by means ofthe residual pressure preventing angular movement ofthe spear valve assembly and the seal between the spear valve and the keg neck will be broken, allowing simultaneous venting of the residual pressure.

2. An assembly according to claim 1 wherein the keyway is formed in the valve body of the spear valve assembly and the opening comprises a substantially vertical slot portion opening into a circumferential or arcuate slot portion, the first recess being a second vertically extending slot portion circumferentially and axially offset from the opening.

3. An assembly according to claim 1 wherein the keyway is a slot configured to the manner of a screw thread in order to draw the spear valve assembly into the keg neck as the key moves along the slot from the opening to its locking position in the first recess.

4. A spear valve assembly for a safety keg assembly according to any of claims 1 to 3.